Grades, ERa, and ER1

ERa is a benchmark; keep at it until you get it right.
ER1 is an exercise; keep at it, and you can learn from your mistakes;
PrGr is a .... well, it can be hard to explain!

US Energy Statistics

We'll look at energy in two different ways. Sometimes, it looks like they don't fit together, but they do!

Generating Electricity: Wind

We'll try making windmills at your desk...

Generating Electricity: Solar

We'll compare the windmills to a solar panel...

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